Evaporation type burner

ABSTRACT

An evaporation type burner which can attain light-up and stable combustion of fuel at an early stage by evenly distributing fuel supplied from a fuel supply part to an impregnation member (wick) inside the impregnation member should be provided includes an exudation prevention member having lower fuel permeability than that of the impregnation member in a surface region of the impregnation member opposite to a infiltration region, which is a surface region of the impregnation member where the fuel infiltrates from the fuel supply part into the impregnation member, across the impregnation member. Preferably, a part of the exudation prevention member is embedded inside of the impregnation member, and another part projects from a surface of the impregnation member. More preferably, the exudation prevention member is constituted as a part of the partition member disposed on a downstream side of the impregnation member in a combustion chamber.

TECHNICAL FIELD

The present invention relates to an evaporation type burner. Morespecifically, the present invention relates to an evaporation typeburner which can attain light-up and stable combustion of fuel at anearly stage.

BACKGROUND ART

Hazardous substances, such as fine particles of soot (PM: ParticulateMatter) and nitrogen oxides (NOx), for example, are contained in exhaustdischarged from an internal combustion engine, such as a diesel engine.Therefore, from the viewpoint of environmental protection, etc., exhaustemission control by preparing a filter (DPF) for collecting the PM andan exhaust purification means such as an NOx reduction catalyst in anexhaust path of an internal combustion engine to removing the PM and NOxhas been performed widely, for example.

By the way, since the PM accumulates on the DPF according to operationof an internal combustion engine, it is necessary to burn theaccumulated PM at a predetermined timing to restore the DPF. Moreover,it becomes difficult to remove NOx by reduction since temperature of thecatalyst is low and the catalyst is not activated when temperature ofthe exhaust is low, for example, on a cold start of the internalcombustion engine, etc. Therefore, in order to remove NOx contained inthe exhaust, it is necessary to raise the temperature of the NOxreduction catalyst up to temperature sufficient for activating the NOxreduction catalyst.

Then, in the art, it has been known to raise temperature of exhaustwhich flows into an exhaust purification means, such as a DPF and a NOxreduction catalyst, by burning fuel in a burner (combustor) disposed inan exhaust path to generate hot combustion gas (for example, refer tothe Patent Document 1 (PTL1)). In accordance with this, opportunities toburn PM accumulated on a DPF to restore the DPF can be increased, and/ortemperature of a NOx reduction catalyst can be quickly raised toactivate the NOx reduction catalyst at an early stage. As a result,hazardous substances (PM and NOx) contained in exhaust discharged froman internal combustion engine can be removed effectively to purify theexhaust. Moreover, it has been also known to use such a burner as aheater for vehicle for heating a cabin of a vehicle (for example, referto the Patent Document 2 (PTL2)).

As a burner as mentioned above, for example, an evaporation type burner,in which fuel is impregnated into a wick (impregnation member) disposedat an end of a combustion chamber and vapor of the fuel generated fromthe wick is heated by a glow plug disposed in the vicinity of the wickto be lit and burned, has been conventionally known. In order toincrease opportunities to restore a DPF, to activate a NOx reductioncatalyst at an early stage and to start heating a cabin of a vehicle atan early stage by using such a burner, it is necessary to attainlight-up and stable combustion of fuel in the burner at an early stage.

In order to do the above, it is desirable to make fuel permeate thewhole wick to evaporate the fuel from the whole surface of the wick.However, when feed rate (supply amount) of fuel is large, for example,at a time point of light-up, etc., the fuel may pass through the wick(exude out of the wick) still in its liquid state before the fuelspreads all over the wick, and it may become difficult to evaporate thefuel from the whole surface of the wick.

Then, in the art, it has been known to arranging a fuel distributionmeans which includes many fuel distribution grooves formed radially froman approximately center part on an inner bottom surface of a casing anddistributes fuel from a fuel supply mechanism throughout the wholesurface of the wick in front of a point where the fuel reaches the wick,in a combustion type heater (evaporation type burner) (for example,refer to the Patent Document 3 (PTL3)). In accordance with this, it isregarded as possible to start operation of the combustion type heaterearlier by shortening transit time for the fuel to spread all over thewick and heat-up time of the wick itself.

However, by newly preparing the fuel distribution means for evenlyspreading fuel all over the wick as mentioned above, problems, such as acomplicated configuration of an evaporation type burner, an increasednumber of parts and increased manufacturing cost, for example, may becaused. Moreover, when feed rate of fuel is small, the fuel may notspread all over the whole fuel distribution grooves (the fueldistribution grooves are not filled with the fuel), but the fuel may becollected (stagnated) at a lower part of the fuel distribution means. Asa result, there is a possibility that it may become difficult to spreadfuel evenly over the whole wick to attain light-up and stable combustionof fuel at an early stage.

CITATION LIST Patent Literature

[PTL1] Japanese Unexamined Utility Model Application Publication No.02-140120

[PTL2] Japanese Utility Model Registration No. 2553419

[PTL3] Japanese Patent No. 3792116

SUMMARY OF INVENTION Technical Problem

As mentioned above, in the art, an evaporation type burner which canattain light-up and stable combustion of fuel at an early stage byevenly distributing fuel supplied from a fuel supply part to animpregnation member (wick) inside of the impregnation member has beendemanded. The present invention has been conceived in order to meet sucha demand.

Solution to Problem

As a result of wholeheartedly research, the inventor has found out thatit is important to prevent fuel from passing through an impregnationmember while the fuel has been a liquid still in its liquid state whensupply amount of the fuel is large, in order to meet a demand asmentioned above.

In view of the above, an evaporation type burner according to thepresent invention (which may be referred to as a “present inventionburner” hereafter) comprises a combustion chamber, an impregnationmember, a fuel supply part, and an igniting device.

The combustion chamber is a space defined by an inside housing that is abottomed cylindrical container consisting of a bottom wall and aperipheral wall. The impregnation member is a member disposed at a firstend that is an end on the bottom wall side of the inside housing in thecombustion chamber and has capillary structure and/or porous structure.The fuel supply part supplies fuel to the impregnation member toimpregnate the fuel into the impregnation member. The igniting deviceheats vapor of the fuel evaporating from the impregnation member tolights up the vapor. Furthermore, a plurality of air-supply holes whichis opened to the combustion chamber and supplies air to the combustionchamber is formed in the peripheral wall of the inside housing.

In addition, the present invention burner further comprises an exudationprevention member which is a member having fuel permeability lower thanthat of the impregnation member. The fuel permeability is acharacteristic value corresponding to permeability of the fuel. Thisexudation prevention member is disposed at least in an opposite regionwhich is a surface region of the impregnation member opposes to ainfiltration region which is a surface region of the impregnation memberwhere the fuel infiltrates into the impregnation member across theimpregnation member.

The exudation prevention member may be an impermeable member throughwhich the fuel cannot permeate. Moreover, the exudation preventionmember may be a member separate from said impregnation member. In thiscase, the exudation prevention member may be connected with saidimpregnation member by sintering.

Furthermore, the whole of the exudation prevention member may beembedded inside of the impregnation member. Alternatively, the whole ofthe exudation prevention member may be disposed outside of theimpregnation member. Alternatively, a part of the exudation preventionmember may be embedded inside of the impregnation member while the otherpart of the exudation prevention member is projected from a surface ofsaid impregnation member. In this case, the part of the exudationprevention member, which is embedded inside of the impregnation member,may be included in the part of the exudation prevention member, which isprojected from the surface of the impregnation member, in a projectiononto a plane perpendicularly intersecting with an axis direction of theinside housing. In addition, a level difference (step) may be formed atan interface between the impregnation member and the part of theexudation prevention member, which is projected from the surface of theimpregnation member.

In one aspect of the present invention, the present invention burnerfurther comprises a partition member disposed at a prescribed intervalfrom the impregnation member on the side nearer to a second end than theimpregnation member in the combustion chamber. The second end is an endon an opposite side to said first end of said combustion chamber. Inaddition, a light-up space which is a space located on the first endside rather than the partition member in the combustion chamber and acombustion space which is a space located on the second end side ratherthan the partition member in the combustion chamber are in communicationwith each other through at least a part of a gap and/or through-holeformed in the partition member.

In this case, the exudation prevention member may be constituted as apart of the partition member. In addition, the partition member does nothave to be connected with the inside housing.

In another aspect of the present invention, the axis direction of theinside housing is a horizontal direction. Furthermore, no air-supplyhole is formed on an upper side in a vertical direction than a tip ofsaid igniting device in said combustion chamber, at least at a position,which is first distance away to said second end side from saidimpregnation member in the axis direction of said inside housing, onsaid peripheral wall of said inside housing. The above-mentioned “firstdistance” is distance between the impregnation member and an air-supplyhole nearest to the impregnation member in the axis direction of theinside housing among the plurality of the air-supply holes.

In this case, the evaporation type burner may be configured such that noair-supply hole is formed on the upper side in the vertical directionthan a center of the combustion chamber, at least at a position, whichis the first distance away to the second end side from the impregnationmember in the axis direction of the inside housing, on the peripheralwall of the inside housing.

Advantageous Effects of Invention

As mentioned above, in the evaporation type burner according to thepresent invention (present invention burner), the exudation preventionmember which has fuel permeability lower than fuel permeability of theimpregnation member is disposed at least in the opposite region. Theabove-mentioned “opposite region” is a surface region of theimpregnation member opposite to a surface region (infiltration region)of the impregnation member where the fuel infiltrates into theimpregnation member, across the impregnation member. Thereby, even whenfeed rate of fuel is large, for example, at a time point of light-up,etc., the possibility that the fuel may pass through the wick (exude outof the wick) still in its liquid state can be reduced.

At least a part of the fuel suppressed from passing through the wick(exuding out of the wick) still in its liquid state by the exudationprevention member in this way is dispersed in directions along theinterface between the exudation prevention member and the impregnationmember. In other words, at least a part of the fuel which has permeatedthrough the impregnation member and has reached the exudation preventionmember is dispersed so as to spread in the inside of the impregnationmember. Therefore, although an impregnation amount (permeation amount)of the fuel to the opposite region of the impregnation member decreases,an area of a region from which the fuel can evaporate in the surface ofthe impregnation member can be increased since the impregnation amount(permeation amount) of the fuel around the opposite region (to an outeredge (periphery) of the opposite region) of the impregnation memberincreases.

As a result, as compared with an evaporation type burner according to aconventional technology (which may be referred to as a “conventionalburner” hereafter) which does not comprise the exudation preventionmember, the fuel can be spread evenly over the whole impregnationmember. Therefore, in accordance with the present invention burner,light-up and stable combustion of fuel can be attained at an earlystage.

Moreover, in a case where a part of the exudation prevention member isembedded inside of the impregnation member while the other part of theexudation prevention member is projected from a surface of theimpregnation member as mentioned above, the part of the exudationprevention member, which is embedded inside of the impregnation member,may be included in the part of the exudation prevention member, which isprojected from the surface of the impregnation member, in a projectiononto a plane perpendicularly intersecting with an axis direction of theinside housing. In other words, the part of the exudation preventionmember, which is projected from the surface of the impregnation member,may extend (spread) along the surface of the impregnation member (forexample, in a shape of a flange).

In accordance with this, even when the fuel which has permeated throughthe impregnation member and has reached the exudation prevention memberoozes out to an outer edge of the opposite region of the impregnationmember along an interface between the impregnation member and the partof the exudation prevention member, which is embedded inside of theimpregnation member, a possibility that “re-impregnation” may occurincreases. The re-impregnation is a phenomenon that fuel spreads alongan interface between the impregnation member and the part of theexudation prevention member, which is projected from the surface of theimpregnation member, and is impregnated into the impregnation memberagain. As a result, a possibility that the fuel may ooze out to theouter edge of the opposite region of the impregnation member along theinterface between the impregnation member and the part of the exudationprevention member, which is embedded inside of the impregnation member,still in its liquid state can be reduced, and the fuel can be morecertainly spread over the whole impregnation member evenly.

Furthermore, a possibility that combustion gas may flow backward to thevicinity of the impregnation member due to pressure fluctuation ofexhaust in association with power variation of an internal combustionengine, etc., for example, and problems such as a misfire and/orcombustion failure may arise in the present invention burner can bereduced by further comprising the partition member as mentioned above.Moreover, in this case, by constituting the preventing member as a partof the partition member as mentioned above, a number of component partscan be reduced and consequently, for example, simplification of amanufacturing process and reduction of a manufacturing cost, etc. can beattained since it becomes unnecessary to connect the partition member tothe inside housing.

In addition, as mentioned above, by forming the air-supply holes nearestto the impregnation member only in a lower region (region on the lowerside in the vertical direction) than the tip of the igniting device orthe center of the combustion chamber when the present invention burneris used in a state where the axis direction of the inside housing is ahorizontal direction, a possibility that flame generated from fuelignited by the igniting device may be blown from the above and therebythe flame may disappear and/or combustion thereof may become unstablecan be reduced.

When the whole exudation prevention member is disposed outside of theimpregnation member, or when a part of the exudation prevention memberis projected from the surface of the impregnation member, an air flowswirling around the exudation prevention member as a center can beproduced by arranging the air-supply holes as mentioned above. Thereby,the flame generated from fuel ignited by the igniting device can spreadeasily along an outer edge of the exudation preventing member, andlight-up and stable combustion of fuel can be attained more certainly atan early stage.

Other objectives, other features, and accompanying advantages of thepresent invention will be easily understood from the followingexplanation about various embodiments of the present invention describedreferring to drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic sectional view of an evaporation type burneraccording to a first embodiment and second embodiment of the presentinvention (first burner and second burner) taken along a plane includingan axis of an inside housing.

FIG. 2 is a schematic plan view when observing the first burner from thedownstream side along the axis direction of the inside housing.

FIG. 3 is a schematic sectional view of the first burner and the secondburner taken along a plane including the line A-A shown in FIG. 2.

FIG. 4 is a schematic sectional view for showing other specific examplesof the exudation prevention member which the first burner and the secondburner comprise.

FIG. 5 is a schematic sectional view for showing various specificexamples of shapes of an embedded part of the exudation preventionmember which the first burner and the second burner comprise.

FIG. 6 is a schematic sectional view for showing one specific example ofa shape of a projected part of the exudation prevention member which thefirst burner and the second burner comprise.

FIG. 7 is a schematic sectional view for showing another specificexample of a shape of the projected part of the exudation preventionmember which the first burner and the second burner comprise.

FIG. 8 is a schematic sectional view for showing further anotherspecific example of a shape of the projected part of the exudationprevention member which the first burner and the second burner comprise.

FIG. 9 is a schematic plan view for showing one modification of thefirst burner that comprises a plurality of igniting devices.

FIG. 10 is a schematic sectional view of an evaporation type burneraccording to a third embodiment of the present invention (third burner)taken along a plane including the axis of the inside housing.

FIG. 11 is a schematic plan view when observing the third burner fromthe downstream side along the axis direction of the inside housing.

FIG. 12 is a schematic plan view for showing one modification of thepartition member which the third burner comprises.

FIG. 13 is a schematic plan view for showing another modification of thepartition member which the third burner comprises.

FIG. 14 is a schematic plan view for showing further anothermodification of the partition member which the third burner comprises.

FIG. 15 is a schematic plan view for showing further anothermodification of the partition member which the third burner comprises.

FIG. 16 is a schematic sectional view of one modification of the thirdburner in which the exudation prevention member is constituted as a partof the partition member, taken along a plane including the axis of theinside housing.

FIG. 17 is a schematic sectional view of one modification of the thirdburner in which the exudation prevention member is constituted as a partof the partition member and partially embedded in the impregnationmember, taken along a plane including the axis of the inside housing.

FIG. 18 is a schematic sectional view of another modification of thethird burner in which the exudation prevention member is constituted asa part of the partition member and partially embedded in theimpregnation member, taken along a plane including the axis of theinside housing.

FIG. 19 is a schematic sectional view of further another modification ofthe third burner in which the exudation prevention member is constitutedas a part of the partition member and partially embedded in theimpregnation member, taken along a plane including the axis of theinside housing.

FIG. 20 is (a) a schematic perspective view, (b) a schematic plan viewwhen observing from the downstream side along the axis direction of theinside housing, and (c) a schematic sectional view taken along a planeincluding the line A-A shown in the above (b), of one modification ofthe third burner in which the partition member and the impregnationmember are connected with each other through the exudation preventionmember constituted as a part of the partition member.

FIG. 21 is (a) a schematic plan view when observing from the downstreamside along the axis direction of the inside housing and (b) a schematicsectional view taken along a plane including the line B-B shown in theabove (a), of the third burner in which the partition member and theimpregnation member connected with each other through the exudationprevention member shown in FIG. 20.

FIG. 22 is a schematic sectional view and partially enlarged view forshowing one modification of a configuration of the partition memberwhich the third burner comprises.

DESCRIPTION OF EMBODIMENTS First Embodiment

Hereafter, an example of a configuration of an evaporation type burneraccording to a first embodiment of the present invention (which may bereferred to as a “first burner” hereafter) will be explained in moredetail referring to drawings.

<Configuration of Burner>

FIG. 1 is a schematic sectional view of the first burner taken along aplane including an axis of an inside housing which defines a combustionchamber. In the following explanation, an upper side in a verticaldirection in a state where the first burner is used (for example, astate where the first burner is mounted on a vehicle, etc.) (upper sideon a page of FIG. 1) is defined as an “upper side”, and a lower sidewhich is opposite side thereto is defined as a “lower side.”Furthermore, a left side when facing the page of FIG. 1 (theimpregnation member side) is defined as an “upstream side” and a rightside which is opposite side thereto is defined as a “downstream side.”

The first burner is an evaporation type burner which comprises acombustion chamber, an impregnation member, a fuel supply part, and anigniting device, as mentioned above. The combustion chamber is a spacedefined by an inside housing that is a bottomed cylindrical containerconsisting of a bottom wall and a peripheral wall. The impregnationmember is a member disposed at a first end that is an end on the bottomwall side of the inside housing in the combustion chamber and hascapillary structure and/or porous structure. The fuel supply partsupplies fuel to the impregnation member to impregnate the fuel into theimpregnation member. The igniting device heats vapor of the fuelevaporating from the impregnation member to lights up the vapor.

The first burner 100 shown in FIG. 1 comprises an outside housing 114and an inside housing 113 disposed inside the outside housing 114.Shapes of the outside housing 114 and the inside housing 113 are notlimited and can be properly designed depending on an intended use andusage environment, etc. of the first burner 100, for example. In thisexample, the outside housing 114 is formed as a cylindrical peripheralwall and the inside housing 113 is formed as a bottomed cylindricalcontainer. This container consists of a peripheral wall 113 a, which iscylindrical and coaxial with the peripheral wall of the outside housing114, and a bottom wall 111, which is disposed at an upstream side end ofthe peripheral wall 113 a (first end).

Between the peripheral wall of the outside housing 114 and theperipheral wall 113 a of the inside housing 113, an air-supply path 115which is a space with its both ends on the upstream side and downstreamside closed is formed. They are configured such that an air inlet 114 awhich is an opening is formed in the peripheral wall of the outsidehousing 114, an air-supply pipe 116 is connected to this air inlet 114a, and air is supplied to the air-supply path 115 in the outside housing114 by an air-supply means which is not shown. A flow rate of the airsupplied to the air-supply path 115 can be arbitrarily changed by a flowrate control part which is not shown.

In this example, the air inlet 114 a is formed in the vicinity of thefirst end of the combustion chamber 110, and the air-supply pipe 116 isconnected to this air inlet 114 a. However, as long as it is possible tosupply air to the inside of the combustion chamber 110, a connectionpoint of the air-supply pipe 116 is not limited in particular.

In addition, a layer of the air supplied through the air-supply path 115formed between the peripheral wall of the outside housing 114 and theperipheral wall 113 a of the inside housing 113 as mentioned above canfunction as a heat insulating layer. As a result, on combustion of fuel,heat inside the combustion chamber 110 can be prevented from beingconducted to the outside housing 114 to give influence caused by heat toequipment other than the first burner 100, etc. A mounting member 117which consists of a flange, etc. is formed at an end on the downstreamside of the outside housing 114 so as to project outward.

The combustion chamber 110 is a space defined by the inside housing 113.The impregnation member 120 is disposed at a first end that is an end onthe side of the bottom wall 111 of the inside housing 113 (upstreamside). Therefore, substantially, a space on the downstream side of theimpregnation member 120 in an interior space of the inside housing 113corresponds to the combustion chamber 110. On the other hand, a secondend (downstream side end), which is an end on the side opposite to thefirst end (upstream side end), of the inside housing 113 is opened as anopening 113 b.

In addition, in this example, an orifice 118 is fitted in the second endof the inside housing 113 to make the cross section of the combustionchamber 110 smaller (namely, a flow channel of combustion gas isnarrowed). This leads to turning a part of combustion gas which hasarrived at the second end of the combustion chamber 110 to the upstreamside to promote mixing of gases in the combustion chamber 110 as well asreturning unburned fuel to the upstream side to burning the fuel.However, a technique for making smaller the cross section of thedownstream part of the combustion chamber 110 is not limited to theabove, an orifice may be formed by bending inward the peripheral wall113 a of the inside housing 113 other than disposing the orifice 118 asa separate part as mentioned above. Moreover, in the evaporation typeburner an according to the present invention, it is not an essentialconstituent element to make smaller the cross section on the second endside of the combustion chamber 110, and an orifice does not have to beformed as mentioned above.

The impregnation member 120 is formed of material which has heatresistance and chemical stability (for example, corrosion resistance,etc.) against fuel, etc. and can be impregnated with fuel in its inside.Specifically, the impregnation member 120 is a member which is formed ofmaterial such as metal and ceramic material and has capillary structureand/or porous structure. In this example, a wick formed by compacting(pressing together) metal fiber and/or ceramic fiber is used as theimpregnation member 120.

Moreover, although a shape of the impregnation member 120 is not limitedin particular, the impregnation member 120 is formed in a shape of adisc, and is disposed so as to cover the whole cross section of thecombustion chamber 110 taken along a plane perpendicularly intersectingwith the axis of the inside housing 113.

A through-hole 111 a is formed in the bottom wall 111 of the insidehousing 113, and a fuel supply pipe 131 is connected to thisthrough-hole 111 a. Thereby, fuel is supplied through the fuel supplypipe 131 from a fuel supply apparatus, which is not shown, to aprincipal surface on the upstream side of the impregnation member 120. Aposition of the through-hole 111 a in the bottom wall 111 (namely,position where the fuel supply pipe 131 is connected to) is not limitedas long as it is possible to supply fuel to the impregnation member 120.In this example, the fuel supply pipe 131 is connected to a position ofthe bottom wall 111 corresponding to the center of the principal surfaceon the upstream side of the impregnation member 120. The above-mentionedfuel supply apparatus and fuel supply pipe 131 constitute the fuelsupply part 130.

Furthermore, an igniting device 140 is disposed at a positioncorresponding to the vicinity of an outside end in a radial direction ofthe impregnation member 120, in the outside housing 114. Specifically,an igniting device mounting member 141 is disposed on a lower side ofthe outside housing 114. The igniting device mounting member 141 isconfigured such that a tip (end on the side of the combustion chamber110) of the igniting device mounting member 141 reaches the inside ofthe air-supply path 115, but does not contact with the inside housing113. Thereby, on combustion of fuel, heat inside the combustion chamber110 can be prevented from being conducted to the outside housing 114through the igniting device mounting member 141 to give influence causedby heat to equipment other than the first burner 100, etc.

An igniting means 142 is fixed to the igniting device mounting member141. The igniting means 142 is not limited in particular as long as itis possible to heat vapor of fuel evaporating from the impregnationmember 120 to light up the vapor, and arbitrary means, such as a sparkplug, can be used, for example. In this example, a glow plug is used asthe igniting means 142.

An arrangement position of the igniting means 142 is not limited inparticular as long as it is possible to heat vapor of fuel evaporatingfrom the impregnation member 120 to light up the vapor. Typically, theigniting means 142 is disposed in the vicinity of the downstream side ofthe impregnation member 120. When the combustion chamber 110 is dividedby the partition member into a light-up space on the upstream side and acombustion space on the downstream side as will be mentioned later, theigniting means 142 is disposed so as to be exposed to the light-upspace. In this example, the igniting means 142 is disposed so as toproject upward in the vicinity of the impregnation member 120 in thecombustion chamber 110 from the peripheral wall 113 a of the insidehousing 113 below the center in an up-and-down direction of theimpregnation member 120.

In the peripheral wall 113 a of the inside housing 113, first air-supplyholes 110 c, which are opened to the upstream side of the combustionchamber 110 and supply air to the combustion chamber 110, and secondair-supply holes 110 d, which are opened to the downstream side of thecombustion chamber 110 and supplies air to the combustion chamber 110,are formed. Hereafter, the first air-supply holes 110 c and the secondair-supply holes 110 d may be collectively referred to as “air-supplyholes”. In this example, the first air-supply holes 110 c which consistsof a plurality of small holes drilled in the peripheral wall 113 a ofthe inside housing 113 are formed at the predetermined interval over thewhole circumferential direction of the peripheral wall 113 a. However,as will be mentioned later, the second air-supply holes 110 d may beformed only in a part of the peripheral wall 113 a (for example, in thelower part, etc.), rather than being formed over the wholecircumferential direction of the peripheral wall 113 a.

The inside housing 113, the outside housing 114, the air-supply pipe116, the impregnation member 120, the fuel supply pipe 131, the ignitingdevice mounting member 141 and the igniting means 142, as well asmembers constituting these and positioning and fixing of membersassociated with these in the first burner 100 can be carried out by awell-known technique such as welding, etc., for example.

Moreover, materials which form various components including the above,which constitute the first burner 100, etc., can be properly chosen anddesigned taking into consideration load, vibration, temperature andpressure, etc., which are expected in a usage environment and usagecondition of the first burner 100. However, since the materials forthese components, etc. is well-known to a person skilled in the art,further explanation will be omitted.

In addition, in FIG. 1, the exudation prevention member which the firstburner 100 comprises is omitted. Although details of the exudationprevention member will be explained in detail later, prior to theexplanation, properties required for the impregnation member will beexplained below, with focus on a relationship with passing through theimpregnation member (exuding out of the impregnation member) of fuel.

<Properties of Impregnation Member>

As properties required for the impregnation member, for example, abilityto hold (be impregnated with) an amount of fuel enough for generating anamount of vapor of the fuel sufficient to light up the fuel by theigniting device and maintain combustion after light-up in the combustionchamber, and ability to quickly disperse the fuel supplied from the fuelsupply part inside the impregnation member by supply pressure from thefuel supply part and/or a capillary phenomenon, etc.

The properties as mentioned above change with an affinity between thefuel and the material which constitutes the impregnation member,minuteness and porosity of internal structure of the impregnationmember, and size and shape of the impregnation member (for example,thickness and area, etc.), etc., for example. However, actually, thereare constraints on the material of constituents which constitutes theimpregnation member, the size and shape of the impregnation member, andthe manufacturing conditions (for example, pressure for compacting(pressing together) the constituents, etc.), naturally.

Moreover, it is thought that the higher the porosity of the impregnationmember is, the more fuels can be held (impregnated) inside theimpregnation member. However, when the porosity is excessively high, itbecomes difficult to hold (impregnate) fuel inside the impregnationmember. As a result, there is a possibility that the fuel still in itsliquid state may flow down to and be collected in a lower part of thecombustion chamber and/or the fuel may pass through the impregnationmember to exude out of the surface of the impregnation member on theopposite side to the fuel supply part still in its liquid state.Conversely, when the porosity is excessively low, although it isnecessary to raise the supply pressure of the fuel by the fuel supplypart in order to make the fuel infiltrate into the inside of theimpregnation member, there is a possibility that the fuel may passthrough the impregnation member to exude out of the surface of theimpregnation member on the opposite side to the fuel supply part stillin its liquid state again, since the amount of the fuel which can beheld (impregnated) inside the impregnation member is small due to thelow porosity.

For the above reasons, in order to prevent fuel from passing through(exuding out of) the impregnation member as mentioned above in theconventional burner, it has been necessary to suppress supply rate offuel by the fuel supply part to be less than a predetermined thresholdaccording to properties of the impregnation member. For this reason, inthe conventional burner, even when it is necessary to raise the supplyrate of fuel, for example, at a time point of light-up, etc., the supplyrate of fuel cannot be sufficiently raised and it is difficult to attainlight-up and stable combustion of fuel at an early stage.

<Mechanism of Passing-Through of Fuel>

Then, as a result of wholeheartedly research, the present inventor hasobtained knowledge as follows. First, on the passing-through(exuding-out) of fuel as mentioned above, thickness of the impregnationmember affects greatly. Specifically, the larger the thickness of theimpregnation member is, the more unlikely to occur the passing-through(exuding-out) of fuel as mentioned above becomes. However, as a matterof design and specification of an evaporation type burner, the thicknessof the impregnation member cannot be enlarged without any limitation.

When the thickness of the impregnation member is kept constant, theminuter the internal structure of the impregnation member becomes(namely, the smaller the porosity thereof becomes), the lower thepermeability of fuel becomes (the more unlikely to exude out the fuelbecomes). Therefore, as mentioned above, in order to maintain the supplyrate of fuel at a desired extent, the minuter the internal structure ofthe impregnation member becomes, the more it is necessary to raise thesupply pressure of fuel by the fuel supply part. However, the minuterthe internal structure of the impregnation member becomes, the lower theporosity of the impregnation member becomes, and the smaller the amountof fuel which can be held (impregnated) inside the impregnation memberbecomes. As a result, the possibility that the fuel may pass through theimpregnation member to exude out of the surface of the impregnationmember on the opposite side to the fuel supply part still in its liquidstate increases.

Moreover, the amount of the fuel which passes through the impregnationmember to exude out of the surface of the impregnation member on theopposite side to the fuel supply part still in its liquid state asmentioned above is also influenced by infiltration rate of the fuel dueto a capillary phenomenon inside the impregnation member. Specifically,the higher the above-mentioned infiltration rate becomes, the larger thedispersion (spread) of the fuel inside the impregnation member becomes,and the amount of the fuel which passes through the impregnation memberstill in its liquid state decreases. Conversely, the lower theabove-mentioned infiltration rate becomes, the smaller the dispersion(spread) of the fuel inside the impregnation member becomes, and theamount of the fuel which passes through the impregnation member still inits liquid state increases.

The infiltration rate of the fuel due to a capillary phenomenon insidethe impregnation member is determined by various factors such asaffinity between the fuel and the material constituting the impregnationmember, as well as the minuteness and porosity of the internal structureof the impregnation member, for example. Therefore, it can be said thatwhether the passing-through (exuding-out) of fuel as mentioned aboveoccurs or not is determined by a balance between the supply pressure ofthe fuel by the fuel supply part and the properties of the impregnationmember (specifically, the infiltration rate of the fuel due to acapillary phenomenon inside the impregnation member and the porosity ofthe impregnation member, etc.).

<Exudation Prevention Member>

Therefore, in the first burner 100, as shown in FIG. 2 and FIG. 3, anexudation prevention member 200 which is a member which has fuelpermeability lower than fuel permeability of the impregnation member 120is disposed on the opposite region at least. As mentioned above, this“opposite region” is a surface region of the impregnation member 120opposite to a surface region of the impregnation member where the fuelinfiltrates into the impregnation member 120 (infiltration region)across the impregnation member 120.

In FIG. 2 and FIG. 3, for the purpose of making easy understanding ofthe present invention, components of the first burner 100, other thanthe combustion chamber 110, the air-supply holes 110 c and 110 d, theinside housing 113, the impregnation member 120, the fuel supply part130, the igniting device 140 and the exudation prevention member 200,are omitted. Moreover, FIG. 2 is a plan view when observing thesecomponents which the first burner 100 comprises from the downstream side(second end side) along the axis direction of the inside housing 113.FIG. 3 is a schematic sectional view of these components which the firstburner 100 shown in FIG. 2 comprises taken along a plane including theline A-A shown in FIG. 2. However, in FIG. 3, for the purpose of makingeasy understanding of the present invention, the air-supply holes 110 cand 110 d which should have not appeared in the sectional view are alsoillustrated.

The infiltration region corresponds to a region where the fuel suppliedto the impregnation member 120 through the inside of the fuel supplypipe 131 contacts with the surface on the first end side of theimpregnation member 120 as shown by a straight arrow illustrated on theleft end of FIG. 3. Moreover, the opposite region where the exudationprevention member 200 is disposed is a surface region on the first endside of the impregnation member 120 opposite to the above-mentionedinfiltration region, and a contact surface between the exudationprevention member 200 and the impregnation member 120 includes theopposite region as apparent from FIG. 2 and FIG. 3.

In addition, the exudation prevention member 200 is a member which hasfuel permeability lower than fuel permeability of the impregnationmember 120 as mentioned above. Here, the “fuel permeability” is an indexof easiness (likelihood) for fuel to permeate, and is a characteristicvalue corresponding to permeability of fuel. As a specific example ofsuch an index, permeability k intrinsic to a medium in the Darcy ruleexpressed by the following formula (1), etc. can be mentioned, forexample.

$\begin{matrix}{\frac{Q}{A} = {{- \frac{k}{\mu}} \times \frac{dp}{dx}}} & (1)\end{matrix}$

In the above formula, Q is a flow rate of fluid (fuel) which passesthrough a medium (the impregnation member 120 and the exudationprevention member 200), A is a cross section of the medium through whichthe fluid passes, p is viscosity of the fluid, and dp/dx is a pressuregradient along a flow channel.

However, a fuel permeability is not limited to the above, and any othercharacteristic values can be employed as the fuel permeability as longas it is an index of easiness (likelihood) for fluid (fuel) to permeatein a medium (the impregnation member 120 and the exudation preventionmember 200) and is a characteristic value corresponding to permeabilityof fluid in the medium.

The exudation prevention member 200 is formed of material which has heatresistance and chemical stability (for example, corrosion resistance,etc.) against fuel, etc. Specifically, the exudation prevention member200 is formed of metal, ceramic material, etc., for example.

The exudation prevention member 200 may be a member which has capillarystructure and/or porous structure (for example, a wick formed bycompacting (pressing together) metal fiber and/or ceramic fiber) justlike the impregnation member 120, or it may be an impermeable memberthrough which the fluid (fuel) cannot permeate.

In the case of the former, at least a part of the fuel which haspermeated through the impregnation member 120 and has reached theexudation prevention member 200 can also permeate through the exudationprevention member 200 to transpire in the combustion chamber 110.Therefore, since the amount of vapor of the fuel supplied to thecombustion chamber 110 increases, it is desirable from a viewpoint ofattaining light-up and stable combustion of the fuel at an early stage.On the other hand, in the case of the latter, since the exudationprevention member 200 does not allow the fuel to permeate, thepossibility that the fuel may pass through the impregnation member 120(wick) (exude out of the impregnation member 120 (wick)) still in itsliquid state can be reduced even when feed rate of the fuel is large,for example, at a time point of light-up, etc.

In addition, the exudation prevention member 200 may be constituted as amember separate from the impregnation member 120. In this case, althougha method for connecting the exudation prevention member 200 and theimpregnation member 120 is not limited in particular, a method which canwithstand heat generated by combustion of the fuel and thermaldeformation due to the heat is desirable. From such a viewpoint, theexudation prevention member 200 may be connected with the impregnationmember 120 by sintering. Specifically, a combination of the exudationprevention member 200 and the impregnation member 120 arranged at apredetermined positional relation can be sintered by heating thecombination, at sintering temperature according to respective materialsof them, for a predetermined time period, for example, in aninfrared-heating furnace, etc., in a state where predetermined pressureis being applied.

<Effectiveness>

In the first burner 100 which has a configuration as mentioned above,the exudation prevention member 200 which has lower fuel permeability ascompared with that of the impregnation member 120 is disposed at leastin the opposite region (opposite to the infiltration region) of theimpregnation member 120. Namely, a region where a possibility that thepassing-through (exuding-out) of fuel may occur is high on the surfaceon the second end side of the impregnation member 120 is covered with amember through which the fuel cannot permeate easily (or at all).

In accordance with the above-mentioned configuration, in the firstburner 100, the possibility that the fuel may pass through theimpregnation member 120 (exude out of the impregnation member 120) stillin its liquid state can be reduced even when feed rate of the fuel islarge, for example, at a time point of light-up, etc.

At least a part of the fuel suppressed from passing through (exuding outof) the impregnation member 120 by the exudation prevention member 200in its liquid state is distributed in a direction along with theinterface between the exudation prevention member 200 and theimpregnation member 120 as shown by the curved arrows illustrated inFIG. 3. In other words, at least a part of the fuel which has permeatedthrough the impregnation member 120 and has reached the exudationprevention member 200 is distributed so as to spread radially inside theimpregnation member 120.

As a result of the above, although the impregnation amount (permeationamount) of the fuel into the opposite region of the impregnation member120 decreases, the impregnation amount (permeation amount) of the fuelaround the opposite region (to an outer edge (periphery) of the oppositeregion) of the impregnation member 120 increases. Therefore, an area ofa region from which the fuel can evaporate in the surface of theimpregnation member 120 is increased. Thus, the first burner 100 canspread the fuel over the whole impregnation member 120 more evenly ascompared with the conventional burner which does not comprise theexudation prevention member 200. Namely, in accordance with the firstburner 100, light-up and stable combustion of fuel can be attained at anearly stage.

<Modification of First Burner>

In the example shown in FIG. 3, the whole exudation prevention member200 is arranged outside the impregnation member 120. In other words, inthe example shown in FIG. 3, the exudation prevention member 200 isarranged on the surface of the impregnation member 120. However,arrangement modes of the exudation prevention member 200 (namely, apositional relation between the impregnation member 120 and theExudation prevention member 200) is not limited to the above.

For example, as shown in (a) of FIG. 4, the whole exudation preventionmember 200 may be embedded inside the impregnation member 120. However,in (a) of FIG. 4, one surface of the exudation prevention member 200 isexposed so as to be flush with the surface on the downstream side(second end side) of the impregnation member 120.

Alternatively, as shown in (b) of FIG. 4, a part of the exudationprevention member 200 may be embedded inside of the impregnation member120 while the other part of the exudation prevention member 200 may beprojected from a surface of the impregnation member.

When the entirety or a part of the exudation prevention member 200 isembedded inside the impregnation member 120 as the examples shown in (a)and (b) of FIG. 4, bond strength (connection strength) between theexudation prevention member 200 and the impregnation member 120 can beraised since the contact area between the exudation prevention member200 and the impregnation member 120 is larger as compared with the casewhere the exudation prevention member 200 is arranged on the surface ofthe impregnation member 120 as shown in FIG. 3.

Furthermore, since the embedded part of the exudation prevention member200 which is a member having relatively low fuel permeability haspenetrated into the inside of the opposite region of the impregnationmember 120, the fuel which has infiltrated into the inside of theimpregnation member 120 from the infiltration region permeates into theinside of the impregnation member 120 so as to avoid this embedded part.Thus, fuel can be more certainly spread over the whole impregnationmember evenly by preparing the embedded part.

In addition, the shape of the part of the exudation prevention member200 which is embedded inside the impregnation member 120 (which may besimply referred to as an “embedded part” hereafter) is not limited inparticular. When the entirety of the exudation prevention member 200 isembedded inside the impregnation member 120, the shape of the crosssection of the embedded part taken along a plane including an axis ofthe inside housing 113 may be a rectangle as shown in (a) of FIG. 4, itmay be a half circle and a triangle as shown in (a) and (b) of FIG. 5,or it may be various shapes including a shape as shown in (c) of FIG. 5.

Also when a part of the exudation prevention member 200 is embeddedinside the impregnation member 120 while the other part of the exudationprevention member 200 is projected from a surface of the impregnationmember 200, the shape of the cross section of the embedded part takenalong a plane including an axis of the inside housing 113 may be arectangle as shown in (b) of FIG. 4, it may be a half circle and atriangle as shown in (d) and (e) of FIG. 5, or it may be various shapesincluding a shape as shown in (f) of FIG. 5.

In FIG. 5, for the purpose of making easy understanding about the crosssectional shape of the embedded part of the exudation prevention member200, only the exudation prevention member 200 and the impregnationmember 120 are extracted and indicated among the components of the firstburner 100.

By the way, as mentioned above, at least a part of the fuel which haspermeated through the impregnation member 120 and has reached theexudation prevention member 200 is distributed so as to spread insidethe impregnation member 120. When the embedded part of the exudationprevention member 200 has penetrated into the inside of the oppositeregion of the impregnation member 120, this effectiveness becomes moreremarkable. Namely, the fuel which has infiltrated into the inside ofthe impregnation member 120 from the infiltration region permeates intothe inside of the impregnation member 120 so as to avoid this embeddedpart. In other words, at least a part of the fuel suppressed frompassing through (exuding out of) the impregnation member 120 by theexudation prevention member 200 in its liquid state is distributed in adirection along with the interface between the exudation preventionmember 200 and the impregnation member 120.

At this time, the fuel which has permeated through the impregnationmember 120 and has reached the exudation prevention member 200 may oozeout to an outer edge of the opposite region of the impregnation member120 along the interface between the impregnation member 120 and the partof the exudation prevention member 200, which is embedded inside of theimpregnation member 120, (embedded part). In this case, at least a partof the fuel which has oozed out is again impregnated into the surface ofthe impregnation member 120. However, when the amount of the fuel whichhas oozed out is large, it may flow down to and be collected in a lowerpart of the combustion chamber 110 without being again impregnated intothe surface of the impregnation member 120.

From a viewpoint of preventing the fuel from oozing out to the outeredge of the opposite region of the impregnation member 120 as mentionedabove, it is desirable that the part of the exudation prevention member200, which is embedded inside of the impregnation member 120, isincluded in the part of the exudation prevention member 200, which isprojected from the surface of the impregnation member 120, in aprojection onto a plane perpendicularly intersecting with the axisdirection of the inside housing 113. In other words, it is desirablethat the part of the exudation prevention member 200, which is projectedfrom the surface of the impregnation member 120, extends (spreads) alongthe surface of the impregnation member 120 (for example, in a shape of aflange), as shown in FIG. 6 to FIG. 8, for example.

In accordance with this, even when the fuel which has permeated throughthe impregnation member 120 and has reached the exudation preventionmember 200 oozes out to an outer edge of the opposite region of theimpregnation member along an interface between the impregnation member120 and the part of the exudation prevention member 200, which isembedded inside of the impregnation member, (embedded part), apossibility that “re-impregnation” may occur increases. There-impregnation is a phenomenon that the fuel spreads along an interfacebetween the impregnation member 120 and the part of the exudationprevention member 200, which is projected from the surface of theimpregnation member, (which may be simply referred to as a “projectedpart” hereafter), and is impregnated into the impregnation member 120again meanwhile.

As a result of the above, a possibility that the fuel may ooze out tothe outer edge of the opposite region of the impregnation member 120along the interface between the impregnation member 120 and the part ofthe exudation prevention member 200, which is embedded inside of theimpregnation member 120, (embedded part), still in its liquid state canbe reduced, and the fuel can be more certainly spread over the wholeimpregnation member 120 evenly.

The longer the route (path) through which the fuel that has penetratedthe impregnation member 120 and has reached the exudation preventionmember 200 oozes out to the outer edge of the opposite region of theimpregnation member 120 becomes, the higher the possibility that theabove-mentioned “re-impregnation” may occur becomes. From such aviewpoint, unevenness (roughness) and/or a level difference, etc. may beformed in the interface between the projected part of the exudationprevention member 200 and the impregnation member 120 to fit with eachother. Furthermore, what is called a “bead” may be formed in theinterface between the projected part of the exudation prevention member200 and the impregnation member 120 to make it difficult for the fuel topass through the interface. In addition, what is called a “liquidreservoir” (concave part) is formed in the interface between theprojected part of the exudation prevention member 200 and theimpregnation member 120 to contain (house) the fuel passing through theinterface therein.

By the way, in the conventional burner which does not comprise theexudation prevention member, it is difficult to make fuel spread evenlyover the whole impregnation member while reducing the passing-through(exuding-out) of the fuel as compared with the first burner 100.Therefore, in the conventional burner, the fuel impregnated inside theimpregnation member tends to be distributed unevenly in a lower part inthe vertical direction of the impregnation member by action of thegravity. In this case, from a viewpoint of improving ignitability offuel, it is desirable to arrange one igniting device in the vicinity ofthe lower part in the vertical direction of the impregnation member.Alternatively, in the conventionally burner, fuel still in its liquidstate, which has passed through the impregnation member may flow downalong the surface on the second end side (downstream side) of theimpregnation member to be collected at a bottom (in a lower part) of thecombustion chamber. In such a case, from a viewpoint of preventing theigniting device from being wet with the fuel still in its liquid state,it is desirable to arrange the igniting device in a position other thanthe vicinity of the lower part in the vertical direction of theimpregnation member.

Similarly, although one igniting device 140 is arranged in the vicinityof a lower part in the vertical direction of the impregnation member 120also in the example of the first burner 100 shown in FIG. 2, the numberand arrangement of the igniting device 140 are not limited to the above.For example, as shown in FIG. 9, a plurality (in FIG. 9, two) of theigniting device 140 may be disposed to raise ignitability of fuel, andthe igniting device 140 may be disposed in a position other than thelower part in the vertical direction of the exudation prevention member200. Furthermore, since the first burner 100 can spread fuel evenly overthe whole impregnation member 120 as mentioned above, degrees of freedomin arrangement of the igniting device 140 is higher as compared with theconventional burner. Specifically, for example, the igniting device 140may be arranged not only in the lower part, but also in the vicinity ofa lateral part and/or an upper part in the vertical direction of theimpregnation member 120.

Although a case where the first burner 100 is used in a state that theaxis direction of the inside housing 113 is a horizontal direction hasbeen mentioned in the above explanation, attitude (posture) of the firstburner 100 (the axis direction of the inside housing 113) in a statewhere the first burner 100 is being used is not limited to a horizontaldirection. Namely, the first burner 100 can be used without any problem,even when the axis direction of the inside housing 113 is a horizontaldirection and a vertical direction, and furthermore in a diagonaldirection inclined to these directions, without any problem, and cansolve the subject to be solved by the present invention can be solvedsuccessfully.

When the first burner 100 is used in a state where the axis direction ofthe inside housing 113 is in a direction other than the horizontaldirection, the side of the impregnation member 120 in the axis directionof the inside housing 113 comes to be an “upstream side”, and theopposite side comes to be a “downstream side.” Moreover, in this case,the direction perpendicularly intersecting with the horizontal directionamong directions perpendicularly intersecting with the axis direction ofthe inside housing 113 comes to be an “up-and-down direction”, the sideupward of the vertical direction comes to be an “upper part” and theside downward of the vertical direction comes to be a “lower part” inthe “up-and-down orientation.”

Second Embodiment

Hereafter, an example of a configuration of an evaporation type burneraccording to a second embodiment of the present invention (which may bereferred to as a “second burner” hereafter) will be explained in moredetail referring to drawings.

<Configuration of Burner>

Except for points which will be explained below, a fundamentalconfiguration of the second burner is the same as that of the firstburner 100 mentioned above while referring to FIG. 1. Therefore,explanation about the fundamental configuration of the second burnerwill be omitted here.

<Exudation Prevention Member>

As mentioned above in the explanation about the first burner 100, as forthe exudation prevention member 200 which the present invention burnercomprises, its entirety may be embedded inside the impregnation member,its entirety may be arranged outside the impregnation member, or a partthereof may be embedded inside the impregnation member while the otherpart thereof may be projected from a surface of the impregnation member.

The exudation prevention member 200 which the second burner compriseshas the “projected part” which is at least a part of the exudationprevention member 200 projected from the surface of the impregnationmember 120 toward the second end side, like the examples shown in FIG.3, (b) of FIG. 4, (d) to (f) of FIG. 5 and FIG. 6 to FIG. 8.

<Effectiveness>

The projected part of the exudation prevention member 200 serves as anobstacle in a space where flame can spread immediately after light-up offuel by the igniting device 140, and the flame comes to spread to vaporof the fuel supplied from the surface of the impregnation member 120exposed to a space where the projected part does not exist. Namely, in aspace on the upstream side (in the vicinity of the impregnation member120) of the combustion chamber 110, in which light-up of the fuel by theigniting device 140 occurs, a region to which the vapor of the fuel issupplied and a region in which flame can spread are sufficiently matchedwith each other, due to the existence of the projected part of theexudation prevention member 200. As a result, since the flame promptlyspreads after the light-up of the fuel by the igniting device 140,stabilization of combustion can be attained at an early stage.

In order to attain the above-mentioned effectiveness, it is desirablethat height (dimension in the axis direction of the inside housing 113)of the projected part of the exudation prevention member 200 from theimpregnation member 120 is large to a certain extent. Specifically, itis desirable that the height of the projected part is nearly equal to ormore than the size (dimension in the axis direction of the insidehousing 113) of the flame generated when the fuel is lit up (ignited) bythe igniting device 140 and thereafter. Moreover, the size of this flameis influenced by a positional relation between the impregnation member120 and the igniting device 140, the supply rate of fuel by the fuelsupply part 130, and the supply rate of air from the air-supply hole 110c (and 110 d), etc. Therefore, the specific height of the projected partcan be determined by a preliminary experiment to which designspecification and operating conditions of the second burner, etc. arereflected, etc., for example.

Third Embodiment

Hereafter, an example of a configuration of an evaporation type burneraccording to a third embodiment of the present invention (which may bereferred to as a “third burner” hereafter) will be explained in moredetail referring to drawings.

<Configuration of Burner>

A fundamental configuration of the third burner is the same as that ofthe above-mentioned first burner 100 and second burner, except that thethird burner further comprises a partition member. Accordingly, aconfiguration of the third burner will be explained below payingattention to the partition member. Therefore, although the exudationprevention member 200 which the third burner 103 comprises is omittedalso in FIG. 10, similarly to FIG. 1, the third burner 103 can comprisevarious exudation prevention members 200 including the exudationprevention member 200 which the above-mentioned first burner 100 andsecond burner may comprise, and the exudation prevention member 200which modifications of the third burner 103 which will be mentionedlater may comprise.

<Partition Member>

The third burner 103 further comprises a partition member 150 disposedat a prescribed interval from the impregnation member 120 on the sidenearer to a second end than the impregnation member 120 (downstreamside) in the combustion chamber 110, as shown in FIG. 10. The second endis an end on an opposite side to the first end of the combustion chamber110. And, a light-up space 110 a, which is a space located on the firstend side (upstream side) of the partition member 150 in the combustionchamber 110, and a combustion space 110 b, which is a space located onthe second end side (downstream side) of the partition member 150 in thecombustion chamber 110, are in communication with each other through atleast a part of a gap and/or through-hole formed in the partition member150.

In addition, in the present invention burner which comprises thepartition member 150 like the third burner 103, the air-supply holewhich is opened to the light-up space 110 a shall be referred to as afirst air-supply hole 110 c, and the air-supply hole which is opened tothe combustion space 110 b shall be referred to as a second air-supplyhole 110 d.

FIG. 11 is a schematic plan view when observing the third burner 103from the second end side (downstream side) along the axis direction ofthe inside housing 113. The partition member 150 shown in FIG. 11 is atabular member in which many through-holes 150 z are formed. However,for example, as shown in FIG. 12, (a) a partition member 150 which hasan array of many through-holes 150 z and (b) a partition member 150which has through-holes 150 z in different shape can also be used.

Moreover, for example, as shown in FIG. 13 and FIG. 14, the partitionmember 150 may be constituted by partition elements 151 a to 151 c orpartition elements 153 a and 153 b, which are a pluralities ofcomponents disposed apart from one another (with gaps among one another)in the axis direction of the inside housing 113 and/or in a directionperpendicularly intersecting with the axis direction of the insidehousing 113. In this case, the light-up space 110 a and the combustionspace 110 b are in communication with each other through a penetrationregion 150 a which is a gap existing among the partition elements shownin the drawings. Namely, in this case, the penetration region 150 a actsas the above-mentioned through-hole 150 z.

In addition, in the partition member 150 shown in FIG. 13 and FIG. 14,each of the partition elements 151 a to 151 c and each of the partitionelements 153 a and 153 b comprise a supporting part 151 s and asupporting part 153 s which are parts having a pillar shape extending inthe axis direction of the inside housing 113, and each of the partitionelements 151 a to 151 c and each of the partition elements 153 a and 153b are supported by the supporting parts 151 s and the supporting parts153 s being inserted in the impregnation member 120. However, a specificmethod for supporting each of the partition elements 151 a to 151 c andeach of the partition elements 153 a and 153 b is not limited to theabove.

Furthermore, for example, as shown in FIG. 15, the partition member 150may be constituted by engaging adjacent partition elements 154 with eachother through a connecting member 155. In addition, the partition member150 may have a combination of various configurations including these.Namely, a specific configuration of the partition member 150 is notlimited in particular as long as the above-mentioned requirements aresatisfied, and can be suitably chosen from various configurationsaccording to design specification and operating conditions of the thirdburner 103, etc., for example.

<Effectiveness>

In the third burner 103 which has the configuration as mentioned above,when the impregnation member 120 and the partition member 150 areobserved from the downstream side, a principal surface on the downstreamside of the impregnation member 120 is at least partially covered withthe partition member 150, and exposed area of the impregnation member120 is reduced. As a result, for example, a possibility that combustiongas may flow backward to the vicinity of the impregnation member 120 inthe combustion chamber 110 due to pressure fluctuation of exhaust inassociation with power variation of an internal combustion engine, etc.,and problems such as a misfire and/or combustion failure may arise canbe reduced.

Moreover, by radiant heat from the partition member 150 heated by flameat the time of combustion of fuel in the combustion chamber 110, theimpregnation member 120 can be warmed effectively to promote evaporationof the fuel from the impregnation member 120 and, as a result, theignitability of the burner can be improved.

Furthermore, fuel-air mixture of vapor of the fuel which evaporates fromthe impregnation member 120 and air supplied into the light-up space 110a through the first air-supply hole 110 c can flow from the light-upspace 110 a into the combustion space 110 b through the partition member150. At this time, by the above-mentioned fuel-air mixture passingthrough the gap and/or through-hole in the partition member 150,concentration of the fuel in the above-mentioned fuel-air mixture can beequalized.

<Modification of Third Burner>

In the third burner 103, the exudation prevention member 200 may beconstituted as a part of the partition member 150. For example, as shownin FIG. 16, a part formed by bending a part (central part) of thepartition member 150 so as to become convex toward the upstream side(first end side) may be used as the exudation prevention member 200(refer to a region surrounded by a broken line in the drawing), and thismay be made to contact with the impregnation member 120.

Alternatively, as shown in FIG. 17 to FIG. 19, a part formed by bendinga part (central part) of the partition member 150 so as to become convextoward the upstream side (first end side) may be used as the exudationprevention member 200 (refer to a region surrounded by a broken line inthe drawing), and a part of this may be embedded in the impregnationmember 120. Also in this case, the cross sectional shape of the embeddedpart of the exudation prevention member 200 may be a rectangle (FIG.17), a triangle (FIG. 18), a half circle (FIG. 19), or other shapes.

In accordance with the above, since the exudation prevention member 200and the partition member 150 can be manufactured integrally, a number ofparts and assembly man hour for the third burner 103 can be reduced, andit leads to reduction of a manufacturing cost as a result. Moreover,since the impregnation member 120 can be warmed effectively to promotethe evaporation of the fuel from the impregnation member 120 also byheat conduction, in addition to the radiant heat from the partitionmember 150 heated by flame at the time of combustion of fuel in thecombustion chamber 110, the ignitability of the third burner 103 can beimproved as a result.

By the way, also when the exudation prevention member 200 is constitutedas a part of the partition member 150 as mentioned above, the exudationprevention member 200 and the impregnation member 120 are connected witheach other by a method, such as sintering, for example. Namely, in thiscase, the partition member 150 and the impregnation member 120 areconnected through the exudation prevention member 200 which is a part ofthe partition member 150.

In the above-mentioned case, the partition member 150 is supported bythe impregnation member 120 through the exudation prevention member 200which is a part of the partition member 150, as shown in FIG. 20, forexample. Therefore, the partition member 150 does not need to beconnected with the inside housing 113. For example, as shown in FIG. 21,the partition member 150 may be supported by the impregnation member 120through the exudation prevention member 200, and may be positioned inthe axis direction of the inside housing 113 by forming stoppers 250 atpredetermined points on the inner wall of the inside housing 113 andbringing a peripheral part of the partition member 150 to contact withthese stoppers 250. As the stopper 250, for example, “cut and raisedpart”, which is a part formed by slitting the inner wall of the insidehousing 113 and making the slit portion project inward, can bementioned, for example. However, a separate member may be fixed at thepredetermined points on the inner wall of the inside housing 113 inplace of the cut and raised part. Thereby, the number of parts andassembly man hour for the third burner 103 can be reduced, and it leadsto reduction of the manufacturing cost as a result.

Although a concave part is formed in the impregnation member 120 and apart of the igniting device 140 is arranged inside the concave part inFIG. 20 and FIG. 21, such an arrangement is not an essential constituentelement of the present invention, the igniting device 140 may bearranged at a position apart to the second end side (downstream side) ofthe impregnation member 120, like the configuration shown in FIG. 1,FIG. 3, FIG. 4, FIG. 6 to FIG. 10 and FIG. 16 to FIG. 19, for example.

By the way, when adopting a tabular partition member, it may becomedifficult to maintain rigidity as the whole partition member, dependingon thickness and area, etc. of plate material (board) constituting thepartition member, for example. In such a case, what is called “burring”can be mentioned as a strategy for enhancing the rigidity of thepartition member. For example, as shown in FIG. 22, the rigidity of thepartition member can be enhanced without taking steps such as thickeningof the partition member, etc., by performing a burring processing tobend and raise a peripheral part of the through-hole 150 z of thepartition member 150 (refer to a region surrounded by a the dash-dotline and its enlarged view B).

Fourth Embodiment

Hereafter, an example of a configuration of an evaporation type burneraccording to a fourth embodiment of the present invention (which may bereferred to as a “fourth burner” hereafter) will be explained in moredetail referring to drawings.

For example, in the first burner 100 shown in FIG. 1, the firstair-supply holes 110 c are formed all over the circumference of theinside housing 113. Also in such a configuration, fuel can be lit up andburned without particular problems, for example, in a case where airsupply rate to the burner is relatively low and in a case where thediameter of the inside housing 113 is large, etc.

However, for example, in a case where air supply rate to the burner isrelatively high and in a case where the diameter of the inside housing113 is small, etc., flame generated by the fuel lit up by the ignitingdevice 140 may be blown out by a flow of air which blows from an upperside of the inside housing 113.

<Configuration of Burner>

Accordingly, in the fourth burner, the axis direction of said insidehousing is a horizontal direction, and no air-supply hole 110 c isformed on an upper side in a vertical direction than a tip of theigniting device 140 in the combustion chamber 110, at least at aposition, which is first distance away to the second end side(downstream side) from the impregnation member 120 in the axis directionof the inside housing 113, on the peripheral wall of the inside housing113. The first distance is distance between the impregnation member 120and an air-supply hole 110 c nearest to the impregnation member 120 inthe axis direction of the inside housing 113 among the plurality of thefirst air-supply holes 110 c and the second air-supply holes 110 d.

More preferably, in the fourth burner, no air-supply hole 110 c isformed on the upper side in the vertical direction than a center of thecombustion chamber 110, at least at a position, which is the firstdistance away to the second end side (downstream side) from theimpregnation member 120 in the axis direction of the inside housing 113,on the peripheral wall of the inside housing 113.

In other words, in the fourth burner, the air-supply hole 110 c nearestto the impregnation member 120 is formed only in a region lower than thetip of the igniting device 140 or the center of the combustion chamber110 (region on the lower side in the vertical direction), in a statewhere the axis direction of the inside housing 113 is a horizontaldirection. Such configurations are shown in FIG. 16 to FIG. 19, FIG. 21and FIG. 22, for example.

<Effectiveness>

In accordance with the above, for example, even in a case where airsupply rate to the burner is relatively high and in a case where thediameter of the inside housing 113 is small, etc., the possibility thatflame generated by the fuel lit up by the igniting device 140 may beblown out by a flow of air which blows from the upper side of the insidehousing 113 is reduced. Moreover, an advantageous effect that flamebecomes more stable is also attained by air being supplied from thelower side.

Moreover, when the exudation prevention member 200 has the projectedpart which is projected from the surface of the impregnation member 120toward the second end side (downstream side) as mentioned above, anadvantageous effect that an air flow swirling around the projected partas a center in the vicinity of the exudation prevention member 120 isproduced and propagation of the flame after light-up (ignition) ispromoted is also attained by limiting the air-supply holes in thevicinity of the igniting device 140 to the lower side as mentionedabove.

Although some the embodiments and modifications having specificconfigurations have been explained sometimes referring to theaccompanying drawings as mentioned above, for the purpose of explainingthe present invention, it should not be interpreted that the scope ofthe present invention is limited to these exemplary embodiments andmodifications, and it is needless to say that any correction can besuitably added within the limits of the matters described in the claimsand the specification.

REFERENCE SIGNS LIST

100: Evaporation Type Burner, 110: Combustion Chamber, 110 a: Light-upSpace, 110 b: Combustion Space, 110 c and 110 d: Air-supply Hole, 111:Bottom Wall of Inside Housing, 111 a: Through-hole of Bottom Wall, 113:Inside Housing, 113 a: Peripheral Wall of Inside Housing, 113 b:Opening, 114: Outside Housing, 114 a: Air Inlet, 115: Air-supply path,116: Air-supply Pipe, 117: Mounting Member, 120: Impregnation Member,130: Fuel Supply Part, 131: Fuel Supply Pipe, 140: Igniting Device, 141:Igniting Device Mounting Member, 142: Igniting Means, 150: PartitionMember, 150 a: Penetration Region, 150 z: Through-hole, 151 a, 151 b,151 c, 153 a and 153 b: Partition Element, 151 s and 153 s: SupportingPart, 154: Partition Element, 155: Connecting Member, 160: Frame, 200:Exudation Prevention Member and 250: Stopper.

1. An evaporation type burner comprising, a combustion chamber which isa space defined by an inside housing that is a bottomed cylindricalcontainer consisting of a bottom wall and a peripheral wall, animpregnation member which is a member disposed at a first end that is anend on said bottom wall side of said inside housing in said combustionchamber and has capillary structure and/or porous structure, a fuelsupply part which supplies fuel to said impregnation member toimpregnate said fuel into said impregnation member, and an ignitingdevice which heats vapor of said fuel evaporating from said impregnationmember to light up said vapor; and a plurality of air-supply holes whichis opened to said combustion chamber and supplies air to said combustionchamber is formed in said peripheral wall of said inside housing,wherein: said evaporation type burner further comprises an exudationprevention member which is a member having lower fuel permeability thatis a characteristic value corresponding to permeability of said fuelthan that of said impregnation member at least in an opposite regionwhich is a surface region of said impregnation member opposite to aninfiltration region which is a surface region of said impregnationmember where said fuel infiltrates into said impregnation member acrosssaid impregnation member, a part of said exudation prevention member isembedded inside of said impregnation member while the other part of saidexudation prevention member is projected from a surface of saidimpregnation member, the part of said exudation prevention member whichis embedded inside of said impregnation member, is included in the partof said exudation prevention member, which is projected from the surfaceof said impregnation member, in a projection onto a planeperpendicularly intersecting with an axis direction of said insidehousing, and a level difference is formed at an interface between saidimpregnation member and the part of said exudation prevention member,which is projected from the surface of said impregnation member.
 2. Theevaporation type burner according to claim 1, wherein: said exudationprevention member is an impermeable member through which the fuel cannotpermeate.
 3. The evaporation type burner according to claim 1 or claim2, wherein: said exudation prevention member is a member separate fromsaid impregnation member.
 4. The evaporation type burner according toclaim 3, wherein: said exudation prevention member is connected withsaid impregnation member by sintering. 5-12. (canceled)
 13. Theevaporation type burner according to claim 1, wherein: the axisdirection of said inside housing is a horizontal direction, and noair-supply hole is formed on an upper side in a vertical direction thana tip of said igniting device in said combustion chamber, at least at aposition, which is first distance away to said second end side from saidimpregnation member in the axis direction of said inside housing, onsaid peripheral wall of said inside housing, and said first distance isdistance between said impregnation member and an air-supply hole nearestto said impregnation member in the axis direction of said inside housingamong the plurality of said air-supply holes.
 14. The evaporation typeburner according to claim 13, wherein: no air-supply hole is formed onthe upper side in the vertical direction than a center of saidcombustion chamber, at least at a position, which is said first distanceaway to said second end side from said impregnation member in the axisdirection of said inside housing, on said peripheral wall of said insidehousing.
 15. The evaporation type burner according to claim 1, wherein:said evaporation type burner further comprises a partition memberdisposed at a prescribed interval from said impregnation member on theside nearer to a second end than said impregnation member in saidcombustion chamber, and said second end is an end on an opposite side tosaid first end of said combustion chamber, and a light-up space which isa space located on said first end side of said partition member in saidcombustion chamber and a combustion space which is a space located onsaid second end side of said partition member in said combustion chamberare in communication with each other through at least a part of a gapand/or through-hole formed in said partition member.
 16. The evaporationtype burner according to claim 15, wherein: said exudation preventionmember is constituted as a part of said partition member.
 17. Theevaporation type burner according to claim 16, wherein: said partitionmember is not connected with said inside housing.